Class: MilkTea::ControlFlow::Builder

Inherits:
Object
  • Object
show all
Defined in:
lib/milk_tea/core/control_flow/builder.rb

Instance Method Summary collapse

Constructor Details

#initialize(ignore_name: nil, binding_resolution: nil, strict_binding_ids: false, local_decl_without_initializer_writes: false) ⇒ Builder

Returns a new instance of Builder.



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 6

def initialize(ignore_name: nil, binding_resolution: nil, strict_binding_ids: false, local_decl_without_initializer_writes: false)
  @ignore_name = ignore_name || ->(_name) { false }
  @binding_resolution = binding_resolution
  @strict_binding_ids = strict_binding_ids
  @local_decl_without_initializer_writes = local_decl_without_initializer_writes
end

Instance Method Details

#add_linear_node(kind, stmt, next_id, reads: Set.new, reads_info: [], writes: Set.new, writes_info: []) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 267

def add_linear_node(kind, stmt, next_id, reads: Set.new, reads_info: [], writes: Set.new, writes_info: [])
  node_id = @graph.add_node(kind:, statement: stmt, line: stmt.line, reads:, reads_info:, writes:, writes_info:)
  @graph.add_edge(node_id, next_id)
  node_id
end

#assignment_target_reads(target, operator) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 277

def assignment_target_reads(target, operator)
  return [Set.new, []] if operator == "="
  return identifier_read_info(target) if target.is_a?(AST::Identifier)

  assignment_target_side_effect_reads(target)
end

#assignment_target_side_effect_reads(target) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 284

def assignment_target_side_effect_reads(target)
  case target
  when AST::Identifier
    [Set.new, []]
  when AST::MemberAccess
    read_identifiers_with_sites(target.receiver)
  when AST::IndexAccess
    receiver_reads, receiver_info = read_identifiers_with_sites(target.receiver)
    merge_read_info!(receiver_reads, receiver_info, *read_identifiers_with_sites(target.index))
    [receiver_reads, receiver_info]
  else
    read_identifiers_with_sites(target)
  end
end

#build(stmts) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 13

def build(stmts)
  @graph = Graph.new
  @graph.exit_id = @graph.add_node(kind: :exit)
  @graph.entry_id = build_block(stmts || [], @graph.exit_id, break_target: nil, continue_target: nil)
  @graph
ensure
  @graph = nil
end

#build_block(stmts, next_id, break_target:, continue_target:) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 48

def build_block(stmts, next_id, break_target:, continue_target:)
  current_next = next_id
  stmts.reverse_each do |stmt|
    current_next = build_statement(stmt, current_next, break_target:, continue_target:)
  end
  current_next
end

#build_loop_body(stmts) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 22

def build_loop_body(stmts)
  @graph = Graph.new
  @graph.exit_id  = @graph.add_node(kind: :exit)         # fall-through (back-edge)
  break_exit_id   = @graph.add_node(kind: :break_exit)   # break target
  @graph.entry_id = build_block(stmts || [], @graph.exit_id, break_target: break_exit_id, continue_target: @graph.exit_id)
  @graph
ensure
  @graph = nil
end

#build_loop_branch(stmts) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 32

def build_loop_branch(stmts)
  @graph = Graph.new
  @graph.exit_id       = @graph.add_node(kind: :exit)
  break_exit_id        = @graph.add_node(kind: :break_exit)
  continue_exit_id     = @graph.add_node(kind: :continue_exit)
  @graph.entry_id      = build_block(
    stmts || [],
    @graph.exit_id,
    break_target:   break_exit_id,
    continue_target: continue_exit_id,
  )
  @graph
ensure
  @graph = nil
end

#build_statement(stmt, next_id, break_target:, continue_target:) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 56

def build_statement(stmt, next_id, break_target:, continue_target:)
  case stmt
  when AST::LocalDecl
    if stmt.else_body
      reads, reads_info = read_identifiers_with_sites(stmt.value)
      writes = Set.new
      writes_info = []
      declaration_key = declaration_binding_key(stmt, stmt.name)
      if declaration_key && (stmt.value || @local_decl_without_initializer_writes)
        writes << declaration_key
        writes_info << { name: stmt.name, binding_key: declaration_key, line: stmt.line, column: stmt.column, origin: :declaration }
      end

      success_id = add_linear_node(:local_decl, stmt, next_id, writes:, writes_info:)
      null_entry = build_block(stmt.else_body, next_id, break_target:, continue_target:)
      condition_id = @graph.add_node(
        kind: :local_decl_condition,
        statement: stmt,
        line: stmt.line,
        reads:,
        reads_info:,
      )
      @graph.add_edge(condition_id, success_id, label: :non_null)
      @graph.add_edge(condition_id, null_entry, label: :null)
      return condition_id
    end

    reads, reads_info = read_identifiers_with_sites(stmt.value)
    writes = Set.new
    writes_info = []
    declaration_key = declaration_binding_key(stmt, stmt.name)
    if declaration_key && (stmt.value || @local_decl_without_initializer_writes)
      writes << declaration_key
      writes_info << { name: stmt.name, binding_key: declaration_key, line: stmt.line, column: stmt.column, origin: :declaration }
    end
    add_linear_node(:local_decl, stmt, next_id, reads:, reads_info:, writes:, writes_info:)
  when AST::Assignment
    reads, reads_info = read_identifiers_with_sites(stmt.value)
    merge_read_info!(reads, reads_info, *assignment_target_reads(stmt.target, stmt.operator))
    merge_read_info!(reads, reads_info, *assignment_target_side_effect_reads(stmt.target))

    writes = Set.new
    writes_info = []
    if stmt.target.is_a?(AST::Identifier)
      target_key = identifier_binding_key(stmt.target)
      if target_key
        writes << target_key
        writes_info << { name: stmt.target.name, binding_key: target_key, line: stmt.line, column: stmt.target.column, origin: :assignment }
      end
    end
    add_linear_node(:assignment, stmt, next_id, reads:, reads_info:, writes:, writes_info:)
  when AST::IfStmt
    fallback_entry = stmt.else_body ? build_block(stmt.else_body, next_id, break_target:, continue_target:) : next_id
    stmt.branches.reverse_each do |branch|
      then_entry = build_block(branch.body, next_id, break_target:, continue_target:)
      branch_reads, branch_reads_info = read_identifiers_with_sites(branch.condition)
      cond_id = @graph.add_node(
        kind: :if_condition,
        statement: branch,
        line: branch.line || stmt.line,
        reads: branch_reads,
        reads_info: branch_reads_info,
      )
      @graph.add_edge(cond_id, then_entry, label: :true_branch)
      @graph.add_edge(cond_id, fallback_entry, label: :false_branch)
      emit_null_test_refinements(cond_id, then_entry, fallback_entry, branch.condition)
      fallback_entry = cond_id
    end
    fallback_entry
  when AST::MatchStmt
    match_reads, match_reads_info = read_identifiers_with_sites(stmt.expression)
    match_id = @graph.add_node(
      kind: :match_condition,
      statement: stmt,
      line: stmt.line,
      reads: match_reads,
      reads_info: match_reads_info,
    )
    if stmt.arms.empty?
      @graph.add_edge(match_id, next_id)
    else
      stmt.arms.each do |arm|
        arm_body = if arm.respond_to?(:body)
                     arm.body
                   else
                     [MilkTea::AST::ExpressionStmt.new(expression: arm.value, line: arm.value.line)]
                   end
        arm_entry = build_block(arm_body, next_id, break_target:, continue_target:)
        if arm.binding_name
          binding_key = declaration_binding_key(arm, arm.binding_name)
          if binding_key
            bind_id = @graph.add_node(
              kind: :match_binding,
              statement: arm,
              line: arm.binding_line || stmt.line,
              writes: Set[binding_key],
              writes_info: [{
                name: arm.binding_name,
                binding_key:,
                line: arm.binding_line || stmt.line,
                column: arm.binding_column,
                origin: :match_binding,
              }],
            )
            @graph.add_edge(bind_id, arm_entry)
            arm_entry = bind_id
          end
        end
        @graph.add_edge(match_id, arm_entry)
      end
    end
    match_id
  when AST::WhileStmt
    condition_reads, condition_reads_info = read_identifiers_with_sites(stmt.condition)
    cond_id = @graph.add_node(
      kind: :while_condition,
      statement: stmt,
      line: stmt.line,
      reads: condition_reads,
      reads_info: condition_reads_info,
    )
    body_entry = build_block(stmt.body, cond_id, break_target: next_id, continue_target: cond_id)
    @graph.add_edge(cond_id, body_entry, label: :true_branch)
    @graph.add_edge(cond_id, next_id, label: :false_branch)
    emit_null_test_refinements(cond_id, body_entry, next_id, stmt.condition)
    cond_id
  when AST::ForStmt
    writes = Set.new
    writes_info = []
    if stmt.name
      loop_key = declaration_binding_key(stmt, stmt.name)
      if loop_key
        writes << loop_key
        writes_info << {
          name: stmt.name,
          binding_key: loop_key,
          line: stmt.line,
          column: stmt.column,
          origin: :for_binding,
        }
      end
    end
    iterable_reads, iterable_reads_info = read_identifiers_with_sites(stmt.iterable)
    header_id = @graph.add_node(
      kind: :for_header,
      statement: stmt,
      line: stmt.line,
      reads: iterable_reads,
      reads_info: iterable_reads_info,
      writes:,
      writes_info:
    )
    body_entry = build_block(stmt.body, header_id, break_target: next_id, continue_target: header_id)
    @graph.add_edge(header_id, body_entry)
    @graph.add_edge(header_id, next_id)
    header_id
  when AST::UnsafeStmt
    build_block(stmt.body, next_id, break_target:, continue_target:)
  when AST::DeferStmt
    body_entry = stmt.body ? build_block(stmt.body, next_id, break_target:, continue_target:) : next_id
    expression_reads, expression_reads_info = stmt.expression ? read_identifiers_with_sites(stmt.expression) : [Set.new, []]
    defer_id = @graph.add_node(
      kind: :defer,
      statement: stmt,
      line: stmt.line,
      reads: expression_reads,
      reads_info: expression_reads_info,
    )
    @graph.add_edge(defer_id, body_entry)
    defer_id
  when AST::ReturnStmt
    return_reads, return_reads_info = read_identifiers_with_sites(stmt.value)
    @graph.add_node(
      kind: :return,
      statement: stmt,
      line: stmt.line,
      reads: return_reads,
      reads_info: return_reads_info,
    )
  when AST::ExpressionStmt
    reads, reads_info = read_identifiers_with_sites(stmt.expression)
    writes, writes_info = write_targets_from_expression(stmt.expression, line: stmt.line)
    if fatal_expression?(stmt.expression)
      @graph.add_node(
        kind: :fatal,
        statement: stmt,
        line: stmt.line,
        reads:,
        reads_info:,
        writes:,
        writes_info:
      )
    else
      add_linear_node(:expression, stmt, next_id, reads:, reads_info:, writes:, writes_info:)
    end
  when AST::StaticAssert
    reads, reads_info = read_identifiers_with_sites(stmt.condition)
    add_linear_node(:static_assert, stmt, next_id, reads:, reads_info:)
  when AST::PassStmt
    add_linear_node(:pass, stmt, next_id)
  when AST::BreakStmt
    target = break_target || next_id
    add_linear_node(:break, stmt, target)
  when AST::ContinueStmt
    target = continue_target || next_id
    add_linear_node(:continue, stmt, target)
  else
    add_linear_node(:other, stmt, next_id)
  end
end

#call_argument_mutation_target(expression) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 473

def call_argument_mutation_target(expression)
  return nil unless expression.is_a?(AST::Call)
  return nil unless expression.callee.is_a?(AST::Identifier)

  callee_name = expression.callee.name
  return nil unless expression.arguments.length == 1

  argument_value = expression.arguments.first.value

  if callee_name == "ref_of"
    return argument_value if argument_value.is_a?(AST::Identifier)
    return nil
  end

  if callee_name == "ptr_of"
    return argument_value if argument_value.is_a?(AST::Identifier)
    return call_argument_mutation_target(argument_value)
  end

  if callee_name == "const_ptr_of"
    return call_argument_mutation_target(argument_value)
  end

  nil
end

#declaration_binding_key(node, name) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 512

def declaration_binding_key(node, name)
  return nil if @ignore_name.call(name)

  if @binding_resolution && (id = @binding_resolution.declaration_binding_ids[node.object_id])
    return id
  end

  return nil if @strict_binding_ids

  name
end

#emit_null_test_refinements(cond_id, true_succ, false_succ, condition) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 524

def emit_null_test_refinements(cond_id, true_succ, false_succ, condition)
  pairs = null_check_pairs(condition, positive: true)
  return if pairs.empty?

  true_refs  = {}
  false_refs = {}
  pairs.each do |key, direction|
    if direction == :non_null_if_true
      true_refs[key]  = :non_null
      false_refs[key] = :null
    else # :null_if_true
      true_refs[key]  = :null
      false_refs[key] = :non_null
    end
  end
  @graph.set_edge_refinement(cond_id, true_succ, true_refs)  unless true_refs.empty?
  @graph.set_edge_refinement(cond_id, false_succ, false_refs) unless false_refs.empty?
end

#fatal_expression?(expression) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/control_flow/builder.rb', line 273

def fatal_expression?(expression)
  expression.is_a?(AST::Call) && expression.callee.is_a?(AST::Identifier) && expression.callee.name == "fatal"
end

#identifier_binding_key(identifier_expression) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 499

def identifier_binding_key(identifier_expression)
  return nil unless identifier_expression.is_a?(AST::Identifier)
  return nil if @ignore_name.call(identifier_expression.name)

  if @binding_resolution && (id = @binding_resolution.identifier_binding_ids[identifier_expression.object_id])
    return id
  end

  return nil if @strict_binding_ids

  identifier_expression.name
end

#identifier_read_info(identifier) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 304

def identifier_read_info(identifier)
  key = identifier_binding_key(identifier)
  return [Set.new, []] unless key

  [Set[key], [ReadSite.new(binding_key: key, line: identifier.line, column: identifier.column, length: identifier.name.to_s.length)]]
end

#merge_null_pairs(left, right) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 578

def merge_null_pairs(left, right)
  left.merge(right) do |_key, left_dir, right_dir|
    left_dir == right_dir ? left_dir : nil
  end.compact
end

#merge_read_info!(reads, reads_info, extra_reads, extra_reads_info) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 299

def merge_read_info!(reads, reads_info, extra_reads, extra_reads_info)
  reads.merge(extra_reads)
  reads_info.concat(extra_reads_info)
end

#mutating_argument_identifier?(expression) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/control_flow/builder.rb', line 467

def mutating_argument_identifier?(expression)
  return false unless expression.is_a?(AST::Identifier)

  @binding_resolution&.mutating_argument_identifier_ids&.key?(expression.object_id)
end

#null_check_pairs(expr, positive:) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 543

def null_check_pairs(expr, positive:)
  case expr
  when AST::UnaryOp
    return null_check_pairs(expr.operand, positive: !positive) if expr.operator == "not"
  when AST::BinaryOp
    case expr.operator
    when "and"
      return merge_null_pairs(null_check_pairs(expr.left, positive:), null_check_pairs(expr.right, positive:)) if positive
    when "or"
      return merge_null_pairs(null_check_pairs(expr.left, positive:), null_check_pairs(expr.right, positive:)) unless positive
    when "=="
      return single_null_pair(expr, positive:, null_on_true: true)
    when "!="
      return single_null_pair(expr, positive:, null_on_true: false)
    end
  end
  {}
end

#read_identifiers(expression, names = Set.new, reads_info = []) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 318

def read_identifiers(expression, names = Set.new, reads_info = [])
  case expression
  when nil
    nil
  when AST::Identifier
    key = identifier_binding_key(expression)
    if key
      names << key
      reads_info << ReadSite.new(binding_key: key, line: expression.line, column: expression.column, length: expression.name.to_s.length)
    end
  when AST::MemberAccess
    read_identifiers(expression.receiver, names, reads_info)
  when AST::IndexAccess
    read_identifiers(expression.receiver, names, reads_info)
    read_identifiers(expression.index, names, reads_info)
  when AST::Specialization
    read_identifiers(expression.callee, names, reads_info)
  when AST::Call
    read_identifiers(expression.callee, names, reads_info)
    expression.arguments.each { |argument| read_identifiers(argument.value, names, reads_info) }
  when AST::UnaryOp
    read_identifiers(expression.operand, names, reads_info)
  when AST::BinaryOp
    read_identifiers(expression.left, names, reads_info)
    read_identifiers(expression.right, names, reads_info)
  when AST::RangeExpr
    read_identifiers(expression.start_expr, names, reads_info)
    read_identifiers(expression.end_expr, names, reads_info)
  when AST::ExpressionList
    expression.elements.each { |element| read_identifiers(element, names, reads_info) }
  when AST::IfExpr
    read_identifiers(expression.condition, names, reads_info)
    read_identifiers(expression.then_expression, names, reads_info)
    read_identifiers(expression.else_expression, names, reads_info)
  when AST::MatchExpr
    read_identifiers(expression.expression, names, reads_info)
    expression.arms.each do |arm|
      read_identifiers(arm.pattern, names, reads_info)
      read_identifiers(arm.value, names, reads_info)
    end
  when AST::MatchStmt
    read_identifiers(expression.expression, names, reads_info)
  when AST::UnsafeExpr
    read_identifiers(expression.expression, names, reads_info)
  when AST::FormatString
    expression.parts.each do |part|
      read_identifiers(part.expression, names, reads_info) if part.is_a?(AST::FormatExprPart)
    end
  when AST::ProcExpr
    nil
  when AST::AwaitExpr
    read_identifiers(expression.expression, names, reads_info)
  when AST::IntegerLiteral, AST::FloatLiteral, AST::StringLiteral,
       AST::BooleanLiteral, AST::NullLiteral,
       AST::SizeofExpr, AST::AlignofExpr, AST::OffsetofExpr
    nil
  else
    nil
  end
  names
end

#read_identifiers_with_sites(expression) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 311

def read_identifiers_with_sites(expression)
  reads = Set.new
  reads_info = []
  read_identifiers(expression, reads, reads_info)
  [reads, reads_info]
end

#single_null_pair(binary_expr, positive:, null_on_true:) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 562

def single_null_pair(binary_expr, positive:, null_on_true:)
  identifier =
    if binary_expr.left.is_a?(AST::Identifier) && binary_expr.right.is_a?(AST::NullLiteral)
      binary_expr.left
    elsif binary_expr.left.is_a?(AST::NullLiteral) && binary_expr.right.is_a?(AST::Identifier)
      binary_expr.right
    end
  return {} unless identifier

  key = identifier_binding_key(identifier)
  return {} unless key

  direction = null_on_true == positive ? :null_if_true : :non_null_if_true
  { key => direction }
end

#write_targets_from_expression(expression, line: nil, writes: Set.new, writes_info: []) ⇒ Object 



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# File 'lib/milk_tea/core/control_flow/builder.rb', line 380

def write_targets_from_expression(expression, line: nil, writes: Set.new, writes_info: [])
  case expression
  when nil
    nil
  when AST::MemberAccess
    write_targets_from_expression(expression.receiver, line:, writes:, writes_info:)
  when AST::IndexAccess
    write_targets_from_expression(expression.receiver, line:, writes:, writes_info:)
    write_targets_from_expression(expression.index, line:, writes:, writes_info:)
  when AST::Specialization
    write_targets_from_expression(expression.callee, line:, writes:, writes_info:)
  when AST::Call
    write_targets_from_expression(expression.callee, line:, writes:, writes_info:)
    expression.arguments.each do |argument|
      value = argument.value
      target_identifier = nil
      if value.is_a?(AST::UnaryOp) && %w[out inout].include?(value.operator) && value.operand.is_a?(AST::Identifier)
        target_identifier = value.operand
      elsif value.is_a?(AST::Identifier) && mutating_argument_identifier?(value)
        target_identifier = value
      else
        target_identifier = call_argument_mutation_target(value)
      end

      if target_identifier
        key = identifier_binding_key(target_identifier)
        if key
          writes << key
          writes_info << {
            name: target_identifier.name,
            binding_key: key,
            line: line,
            column: nil,
            origin: :call_argument,
          }
        end
      end
      write_targets_from_expression(value, line:, writes:, writes_info:)
    end
  when AST::UnaryOp
    write_targets_from_expression(expression.operand, line:, writes:, writes_info:)
  when AST::BinaryOp
    write_targets_from_expression(expression.left, line:, writes:, writes_info:)
    write_targets_from_expression(expression.right, line:, writes:, writes_info:)
  when AST::RangeExpr
    write_targets_from_expression(expression.start_expr, line:, writes:, writes_info:)
    write_targets_from_expression(expression.end_expr, line:, writes:, writes_info:)
  when AST::ExpressionList
    expression.elements.each do |element|
      write_targets_from_expression(element, line:, writes:, writes_info:)
    end
  when AST::IfExpr
    write_targets_from_expression(expression.condition, line:, writes:, writes_info:)
    write_targets_from_expression(expression.then_expression, line:, writes:, writes_info:)
    write_targets_from_expression(expression.else_expression, line:, writes:, writes_info:)
  when AST::MatchExpr
    write_targets_from_expression(expression.expression, line:, writes:, writes_info:)
    expression.arms.each do |arm|
      write_targets_from_expression(arm.pattern, line:, writes:, writes_info:)
      write_targets_from_expression(arm.value, line:, writes:, writes_info:)
    end
  when AST::UnsafeExpr
    write_targets_from_expression(expression.expression, line:, writes:, writes_info:)
  when AST::FormatString
    expression.parts.each do |part|
      write_targets_from_expression(part.expression, line:, writes:, writes_info:) if part.is_a?(AST::FormatExprPart)
    end
  when AST::AwaitExpr
    write_targets_from_expression(expression.expression, line:, writes:, writes_info:)
  when AST::ProcExpr,
       AST::Identifier,
       AST::IntegerLiteral,
       AST::FloatLiteral,
       AST::StringLiteral,
       AST::BooleanLiteral,
       AST::NullLiteral,
       AST::SizeofExpr,
       AST::AlignofExpr,
       AST::OffsetofExpr
    nil
  else
    nil
  end

  [writes, writes_info]
end